聚乳酸微塑料对小麦种子萌发和幼苗功能性状的影响OACHSSCD

To assess the ecological risks of biodegradable polylactic acid microplastics(PLA-MPs)to crops,this study investigated the effects of PLA-MPs on seed germination and seedling functional traits of wheat(Triticum aestivum).Ex-periments were conducted using germination tests and hydroponic cultures.Wheat seeds and seedlings were exposed to two particle sizes(25 and 150 μm)of PLA-MPs at four concentrations(0,50,200,and 1 000 mg·L-1).Results indicated that PLA-MPs significantly inhibited key germination parameters.Compared to the control,PLA-MPs reduced the final germination percentage(GP),germination vigor(GV)and germination index(GI),while prolonging the mean germina-tion time(MGT).High-concentration treatments(1 000 mg·L-1)induced a higher incidence of root rot and decreased the root-shoot ratio.At the seedling stage,PLA-MPs exposure elicited substantial physiological and morphological disturb-ances.PLA-MPs triggered oxidative damage,evidenced by the accumulation of reactive oxygen species(ROS)and in-creased malondialdehyde(MDA)content.Root system architecture was adversely affected,showing significant inhibition of root growth and a decline in root activity.Photosynthetic function was impaired,as reflected in reduced chlorophyll con-tent and inhibited photosynthetic efficiency.Consequently,specific leaf area(SLA)increased significantly,while leaf dry matter content(LDMC)and the uptake of essential macronutrients(nitrogen,phosphorus and potassium)were markedly reduced.Two-way analysis of variance(ANOVA)revealed that concentration was the primary factor influencing wheat seed germination and seedling functional traits,with particle size exerting a secondary effect.Significant interactions between concentration and particle size were observed for only a minority of the measured indicators.Principal component analysis(PCA)further confirmed the significant particle size-and concentration-dependent effects of PLA-MPs on wheat.The phytotoxicity of PLA-MPs intensified with decreasing particle size and increasing concentration.Smaller particles(25 μm)and higher concentrations(200 and 1 000 mg·L-1)consistently induced more pronounced detrimental effects across most measured parameters compared to larger particles(150 μm)and lower concentrations.These findings demonstrate that bio-degradable PLA-MPs pose significant physiological and morphological threats to wheat,a staple crop.The toxicity is con-centration-dependent and particle size-specific,with higher concentrations and smaller sizes causing greater harm.This study provides critical evidence for evaluating the ecological risks posed by biodegradable microplastics in agricultural sys-tems and underscores the need for further investigation into their long-term environmental impacts.